Weapons add a violent dynamic that is often missing in normal training. We get rapped knucles, the occasional bonk on the wrist, elbow or head, and no mention is made. The obvious task is to develop speed, power, and timing in the midst of good technique; there is an element of real danger if not careful. Obviously, the result of such training will carry over to one's Aikido - increased alertness, a more imperative awareness of space, the need to avoid, the desire to receive a more dynamic attack, etc. It is not easy to get that in Aikido without weapons, but if you can, then fair enough.